Paper feeding unit

Abstract

A paper feeding unit includes: a detecting board formed of a regular-polygonal prism having a multiple number of sensors; a detection block with sides which each have a multiple number of signal generating portions and are able to face the sensors; a holder portion holding the detection block so as to allow the posture of the block to be changed to fix the block at setup positions; and a display window which allows a paper-size indicator displayed on the signal generating portions of the detection block to be seen from the outside. In this configuration, the orientation and position of the detection block are adapted to be changed in accordance with the size of paper held in the paper feed cassette.

What is claimed is: 
     
       1. A paper feeding unit comprising: a paper holding receptacle capable of positioning and holding sheets of paper of a size selected from a plurality of different sizes;   a paper feeding mechanism for separating sheets of paper held on said paper holding receptacle, one by one and feeding the separated sheets therefrom;   a holder portion disposed in said paper holding receptacle;   a detection block being held in said holder portion in such a manner that a posture or position of said detection block, indicative of the size of paper held by said paper holding receptacle, can be moved;   a plurality of sensors disposed opposite to said detection block for generating detection signals based on the posture or position of said detection block as held in said holder portion, the detection signals being indicative of the size of paper; and   indicating means for displaying the size of paper held by said paper holding receptacle based on the detection signals generated by said plurality of sensors,   said detection block being a regular-polygonal prism with at least one side face having a plurality of signal generating portions which face said plurality of sensors.   
     
     
       2. The paper feeding unit of claim 1, wherein each of said plurality of sensors comprise: a light emitter for emitting light toward a respective one of said plurality of signal generating portions of said detection block; and   a light receiver for receiving the emitted light reflected by the respective one of said plurality of signal generating portions and generating a corresponding one of the detection signals in accordance with the received light.   
     
     
       3. The paper feeding unit of claim 2, wherein said at least one side face of said regular-polygonal prism includes a plurality of reflective surfaces as said plurality of signal generating portions and non-reflective portions which do not reflect the emitted light from said light emitter. 
     
     
       4. The paper feeding unit of claim 3, wherein said non-reflective portions comprise holes formed in said at least one side face of said regular-polygonal prism. 
     
     
       5. The paper feeding unit of claim 1, wherein said regular-polygonal prism has a plurality of side faces having further signal generating portions, each of said plurality of side faces having respective projections at opposite longitudinal first and second ends, said holder portion having plural slots formed therein, the posture or position of said regular-polygonal prism within said holder portion being selectable according to which of said plural slots said projections are placed in.   
     
     
       6. The paper feeding unit of claim 5, wherein the posture or position of said regular-polygonal prism within said holder portion is selectable in a longitudinal direction of said regular-polygonal prism in accordance with which of said plural slots said projections are placed in. 
     
     
       7. The paper feeding unit of claim 1, wherein said regular-polygonal prism has a plurality of side faces having further signal generating portions, said regular-polygonal prism being rotatable about a longitudinal axis such that said plurality of side faces are movable within said holder portion to face said plurality of sensors. 
     
     
       8. The paper feeding unit of claim 1, wherein said paper holding receptacle comprises a display window, said plurality of signal generating portions having paper-size indicators formed thereon viewable through said display window.   
     
     
       9. A paper feeding unit comprising: a paper holding receptacle capable of positioning and holding sheets of paper of a size selected from a plurality of different sizes;   a paper feeding mechanism for separating sheets of paper held on said paper holding receptacle, one by one and feeding the separated sheets therefrom;   a detection block disposed in said paper holding receptacle;   a holder portion holding said detection block such that said detection block can be rotationally moved or axially shifted and can be fixed at setup positions indicative of the size of paper held by said paper holding receptacle;   a plurality of sensors disposed opposite to said detection block for generating detection signals based on the setup position of said detection block, the detection signals being indicative of the size of paper; and   indicating means for displaying the size of paper held by said paper holding receptacle based on the detection signals generated by said plurality of sensors,   said detection block being a regular-polygonal prism with at least one side face having a plurality of signal generating portions which face said plurality of sensors, said indicating means displaying a paper-size indicator formed on said signal generating portions of said detection block.   
     
     
       10. The paper feeding unit of claim 9, wherein each of said plurality of sensors comprise: a light emitter for emitting light toward a respective one of said plurality of signal generating portions of said detection block; and   a light receiver for receiving the emitted light reflected by the respective one of said plurality of signal generating portions and generating a corresponding one of the detection signals in accordance with the received light.   
     
     
       11. The paper feeding unit of claim 10, wherein said at least one side face of said regular-polygonal prism includes a plurality of reflective surfaces as said plurality of signal generating portions and non-reflective portions which do not reflect the emitted light from said light emitter. 
     
     
       12. The paper feeding unit of claim 11, wherein said non-reflective portions comprise holes formed in said at least one side face of said regular-polygonal prism. 
     
     
       13. The paper feeding unit of claim 9, wherein said regular-polygonal prism has a plurality of side faces having further signal generating portions, each of said plurality of side faces having respective projections at opposite longitudinal first and second ends, said holder portion having plural slots formed therein, the posture or position of said regular-polygonal prism within said holder portion being selectable according to which of said plural slots said projections are placed in.   
     
     
       14. The paper feeding unit of claim 13, wherein the posture or position of said regular-polygonal prism within said holder portion is selectable in a longitudinal direction of said regular-polygonal prism in accordance with which of said plural slots said projections are placed in. 
     
     
       15. The paper feeding unit of claim 9, wherein said regular-polygonal prism has a plurality of side faces having further signal generating portions, said regular-polygonal prism being rotatable about a longitudinal axis such that said plurality of side faces are movable within said holder portion to face said plurality of sensors. 
     
     
       16. The paper feeding unit of claim 9, wherein said paper holding receptacle comprises a display window, said plurality of signal generating portions having paper-size indicators formed thereon viewable through said display window.   
     
     
       17. A paper feeding unit comprising: a paper feed cassette composed of a cassette body capable of accommodating sheets of paper of a size selected from a plurality of different sizes and fixing plates for positioning said sheets of paper of different sizes; and   a paper feeding mechanism for separating sheets of paper held by said paper feed cassette, one by one and feeding the separated sheets therefrom,   said paper feed cassette further including a front cover disposed in such a position as to be externally viewable, said front cover being provided with a detecting board having a plurality of sensors,   a detection block composed of a regular-polygonal prism with at least one side face having a plurality of signal generating portions which face said plurality of sensors,   a holder portion holding said detection block such that said detection block can be rotationally moved or axially shifted and can be fixed at setup positions indicative of the size of paper held by said paper feed cassette, and   a display window which displays a paper-size indicator displayed on said signal generating portions of said detection block.     
     
     
       18. A paper holding receptacle for a paper feeding unit, the paper holding receptacle capable of holding sheets of paper of a size selected from a plurality of different paper sizes, comprising: a holder;   a regular-polygonal prism, manipulable within said holder to one of plural positions, for providing indication of the size of paper held by the paper holding receptacle, each of the plural positions being indicative of a respective different paper size;   a plurality of sensors disposed in the vicinity of said regular-polygonal prism for generating detection signals based on the position of said regular-polygonal prism as held in said holder, the detection signals being indicative of the size of paper held by the paper holding receptacle; and   display means for displaying the size of paper held by the paper holding receptacle in accordance with the detection signals.   
     
     
       19. The paper holding receptacle of claim 18, wherein said regular-polygonal prism has at least one side face having a plurality of signal generating portions which face said plurality of sensors, each of said plurality of sensors comprising: a light emitter for emitting light toward a respective one of said plurality of signal generating portions of said regular-polygonal prism; and   a light receiver for receiving the emitted light reflected by the respective one of said plurality of signal generating portions and generating a corresponding one of the detection signals in accordance with the received light.   
     
     
       20. The paper holding receptacle of claim 19, wherein said at least one side face of said regular-polygonal prism includes a plurality of reflective surfaces as said plurality of signal generating portions and non-reflective portions which do not reflect the emitted light from said light emitter. 
     
     
       21. The paper holding receptacle of claim 20, wherein said non-reflective portions comprise holes formed in said at least one side face of said regular-polygonal prism. 
     
     
       22. The paper holding receptacle of claim 18, wherein said regular-polygonal prism has a plurality of side faces each having a plurality of signal generating portions and respective projections at opposite longitudinal first and second ends, said holder having plural slots formed therein, the position of said regular-polygonal prism within said holder being selectable according to which of said plural slots said projections are placed in.   
     
     
       23. The paper holding receptacle of claim 22, wherein the position of said regular-polygonal prism within said holder is selectable in a longitudinal direction of said regular-polygonal prism in accordance with which of said plural slots said projections are placed in. 
     
     
       24. The holding receptacle of claim 18, wherein said regular-polygonal prism has a plurality of side faces each having a plurality of signal generating portions, said regular-polygonal prism being rotatable about a longitudinal axis such that said plurality of side faces are movable within said holder to face said plurality of sensors. 
     
     
       25. The paper holding receptacle of claim 18, wherein said plurality of signal generating portions have paper-size indicators formed thereon viewable through said display means.